TypescriptTutor

Daily TS tips and answered questions

[TypescriptTutor @TypescriptTutor]

Oh boy do I appreciate having optional chaining in #TypeScript

[TypeScript @typescript]

🥳🎉 TypeScript 4.0 is here! 🎉🥳

Read up on what's new and get it today!

https://t.co/gVDik8g7Pb

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What feature are you most excited in #Typescript v4?
https://t.co/EypLhKhvcN

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Which go you use more often?

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Leave a comment with “why”

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In your TS projects which do you prefer?

[TypescriptTutor @TypescriptTutor]

As of Typescript 3.7, you can use the “?.” syntax called “Optional Chaining” to safely navigate deep properties that might be undefined.

https://t.co/mtLeQCJO5d

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@LolindirLink @Sosowski Let me know if I can ever clarify anything with Typescript!

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Use an abstract class to define methods to be implemented in classes that extend it. Typescript will throw compiler errors if they aren’t implemented correctly.

https://t.co/W5gwGoYWJH

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@wfxpanisa @housecor Let me know if I can help in the process!

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@swyx @justincunn @DanWahlin @typescript 💯

[TypescriptTutor @TypescriptTutor]

A nice little treat from Typescript 3.8, you can now export * as namespace! Check it out!

[TypescriptTutor @TypescriptTutor]

Have a hard time remembering the difference between for..in and for..of loops?

for *in* iterated *IN*dexes

for *of* iterates *o*bjects (or the elements of the iterable)

[TypescriptTutor @TypescriptTutor]

@setfloat @aaronfrost @typescript @angular Got it! The “!” is applied to the final result (either baz or undefined)

Exactly the same as !https://t.co/OrgOnroBZq.baz would (without throwing an error if foo or bar are undefined)

[TypescriptTutor @TypescriptTutor]

@Madisonkanna @swyx @typescript I’m happy to help as well! Feel free to reach out!

[TypescriptTutor @TypescriptTutor]

@setfloat @aaronfrost @typescript @angular foo?.bar?.baz will return either the value of “baz” or undefined if any step along the chain doesn’t exist.

[TypescriptTutor @TypescriptTutor]

The “Parameters” built-in utility type returns a tuple type describing the arguments passed to a provided function signature.

Any terms there you don’t understand? Just ask! There’s no such thing as a bad question.

https://t.co/pmq8Y49jh1

[TypescriptTutor @TypescriptTutor]

@BryanMigliorisi @SeaRyanC @drosenwasser I can’t explain *why* this is. But when I use arrow functions (particularly for the first function) the inference is working for me.

inferenceDoesntWork({
firstFunction: () => true,
secondFunction: a => a,
}),

[TypescriptTutor @TypescriptTutor]

@tin_r Worth giving it a try! Feel free to let me know if you have any questions as you go!

[TypescriptTutor @TypescriptTutor]

The “NonNullable” built-in utility type removes the possibility of `undefined` or `null` from a type.

https://t.co/x0K61cHbCY